Composite wheels are increasingly employed because of their weight and other advantageous shape conditions, wherein wheel rim and hub are separately produced by possibly different manufacturing methods, and then are connected to each other. A composite two-part wheel of this type is shown, for example, in FIG. 2 of British patent No. 1,316,954. This kind of composite wheel has a wheel rim with a recessed base as one part, and a hub as another part, and these are connected to each other by bolts welded to the outer side of the a flange on the recessed base. After the initial mounting of hub and wheel rim the bolt is passed through an opening in the outer edge of the hub and is then welded to the wheel rim. Finally the head is formed on the free end of the bolt and thus a tight connection is formed which cannot be loosened. The advantage of this structure is that the radial forces and a large part of the axial forces act on the connecting means and thus its load bearing ability is limited.
German published patent application 4,019,649 shows a similar construction of a composite wheel. This wheel has a wheel rim with a recessed base. The wheel rim in the area of the base has a radially inwardly extending flange with holes for bolts distributed throughout its circumference. The single part hub has in its outer peripheral circumference an area which mates the flange of the wheel rim, and also has bolt holes distributed over its circumference. Bolts are placed in the holes of the wheel rim and the hub, with nuts on them for a strong connection between the two parts. It is a disadvantage of this vehicular wheel that, it has a structural limitation in that the flange of the wheel rim can be produced only by casting or through complex forging operations with subsequent mechanical processing. A further disadvantage is that the wheel rim is a cast body which must be produced with thick walls for transferring the required forces, instead of a wheel rim produced by rolling or pressing. This is a unfavorable factor due to its large weight.
German utility model 9,014,530 shows a similarly constructed composite wheel. The wheel rim which has a well base is provided in the area of the well base with a ring shaped thickening of the material on the inner or outer surface of the wheel. A number of circumferential threaded bores are arranged around the circumference of this thickened portion, parallel to the axis of the wheel. The disk shaped hub has openings in the area of its outer circumference, which correspond to the threaded bores. These openings serve for passing the bolts through them so that a strong connection can be established between the wheel rim and the hub. This composite wheel can also not be considered to be optimal from the point of view of weight, since the required amount of material in the recessed base area of the wheel rim can be only obtained by casting and a complex forging procedure.
A composite vehicular wheel with a single part wheel rim and a hub attached to it by bolts, is shown in German published patent application 3,915,595. Similarly to the disclosure of the aforementioned German published patent application 4,019,694, the wheel rim has a radially inward flange on the inner side and this is bolted to the hub. The disadvantage of this structure is that the flange can be formed only by casting and complex forging thereafter. The alternative suggestion of welding such a flange on the wheel rim is also disadvantageous since the total forces pass through the weld and therefore subjects it to high loadings.